The invention relates to a shaft rod for weaving machines and a heald shaft having at least one such a shaft rod.
Heald shafts are subject to increasing requirements concerning their load bearing capacity. Such requirements originate in the increasing operating speed (rpm) of the weaving machines which, for economical reasons, have to operate with an ever increasing output and thus an ever increasing productivity. To be able to construct, within the limited structural space of a weaving machine, a heald shaft which may satisfy the above requirements, shaft rods are necessary which, in the first place, are highly resistant to bending in the direction of motion which, as a rule, is vertical.
In the prior art various proposals are known concerning the configuration of shaft rods. Only a few of such proposals, however, have proved to be practical. For example, German Patent Document No. DE 39 37 657 discloses a shaft rod composed of side parts and reinforcing sections. The manufacture of such shaft rods, however, involves substantial outlay and is therefore expensive.
German Patent Document No. DE 41 01 512 discloses an arrangement which is limited to the use of steel. Such a construction has met with some success because of the use of relatively inexpensive materials. Weight considerations, however, set limits to such a construction.
A further proposal is set forth in European Patent Document No. EP 0 288 652. The proposed excessive use of expensive fiber reinforcements is, however, a substantial impediment to an economic success.
An interesting arrangement is described in German Patent Document No. DE 103 49 382 which discloses the manufacture of a shaft rod, starting from a single-chamber or multi-chamber extruded aluminum member which is provided at its ends with a reinforcing element running out in a wedge-shaped manner. The reinforcing element is glued to the aluminum body. For introducing the reinforcing element into the aluminum body, for example, an originally closed chamber of the extruded aluminum member is opened at least toward one side by partially removing the wall of the extruded member present in that region. The reinforcing element may be introduced through the thus-obtained elongated opening into the shaft rod and glued thereto. Based on this concept, light-weight, yet rigid shaft rods may be economically manufactured. However, difficulties are encountered in securing driving elements to such a shaft rod. Further, the adhesive bond between the reinforcing element and the shaft rod may prove to be the weak region of the construction.
It is the object of the invention to provide an improved shaft rod.